The US Centers for Disease Control and Prevention estimate that 1.6 - 3.8 million concussions occur annually. Although striking, these figures are vast underestimates of the actual number of afflicted individuals because many who have suffered a concussion are never diagnosed because they do not seek medical advice. During competition and practice, athletes are at a relatively high risk of sustaining a concussion injury. Undiagnosed or ignored concussion may lead to a prolonged recovery or place the athlete at risk for a potentially more damaging secondary concussion. The risk of both premature return-to-play and secondary impact is exacerbated by the lack of quick and reliable side-line concussion assessment following the initial brain injury. Currently available field-side tools assess attention, memory, and balance, but have not been shown to provide an adequate set of reliable and objective measures. The proposed research program aims to protect athletes (youth through adult) from the negative effects of missed-diagnosis and premature return-to-play by providing a fast and objective field-side oculomotor function evaluation. This additional oculomotor function information, which is physiologically unique from the measures currently available side-line, will make a significant improvement in the current side-line assessment best-practices. The proposed mobile Sports-Concussion Oculomotor Response Evaluation (mobileSCORE ) system provides a field-side objective metric to assist the removal-from-play decision and protect athletes. MobileSCORE is operationalized using mobile devices already readily available field-side during the entire athletic season, allows baseline data and history of prior concussions to be collected field-side during preseason, and provides an objective assessment metric following a potential head trauma during practice or competition. The mobileSCORE system administers a suite of oculomotor function tasks (which are currently used effectively for concussion diagnosis in clinical settings), collects the resulting visual-tracking data, and analyzes the tracking data using statistical change-detection (in comparison to the individual's baseline data) to provide a quantitative concussion assessment metric. Task presentation, data collection, and data analysis are all accomplished using the standard iPad display, video camera, and processor; thus eliminating the need for specialized visual-tracking hardware and facilitating oculomotor testing in a field-side setting. MobileSCORE will protect athletes by reducing instances of missed head trauma and premature return-to-play, thereby reducing recovery time and risk of a second, typically more damaging, brain injury.